Production of monopotassium phosphate



Patented July 5, 1932 WALTHER SGI-IUPPE, or BERLIN,GERMA1'Y PRODUCTIONOF MON OPOTASSIUM PHQSPHA'IE 'No Drawing. Application filed. October-10,1930, Serial no.. 4s7,9o9, and in Germany October 25, 1929.

My invention refers to the production of mono-potassium phosphate. a 1

In Letters Patent of the United, States No. 1,805,873 a method ofproducing mono- 5 potassium phosphate from phosphoric acid and potassiumchloride is disclosed which comprises operating two stages, firstproducing the double salt KH PO ILPO by heat ing potassium chloride witha quantity, in i0 phosphoric acid, until the hydrochloric acid has beenexpelled and decomposing theacid salt obtained after cooling with somuch water that mono-phosphate is separated out and a liquor formed,which is saturated with the .mono-phosphate (KI-I POQ and with thedouble salt mentioned above. This double salt is either first isolatedfrom the mother liquor and thereafter decomposed with a tioned above,being a solutionsaturated bothwith mono-potassium phosphate and with Ithe double salt KH PO .H PO Into this solution potassiumchloride andphosphoric acid are introduced in molecularproportion,

the mixture is heated and under boiling the chlorine is expelled in theform of hydrochloric acid. The percentage of phosphoric acid in thereaction mixture and consequently also the reaction velocity can bevaried by varying the proportion of the quantity of the starting liquorto the quantities of the excess of the molecular quantity of dilute.

solution of mono-potassium phosphate or compounds introduced into it.During the heating the reaction mixture is agitated in, air or by someother suitable means. The percentage of water in the reaction mixture.

is kept constant'by returning the condensate:

either by a mechanical stirreror by blowing duction of steam or byother-means; When I the reaction has come to an end, the hot solu-. tionis cooled and mono-potassium phosphate 1s obtained as a precipitate,while the supernatant mother liquor corresponds to the starting liquor,being saturated with monopotassium phosphate and the double salt, so.ghat it can be reused in a succeeding operaion.

The crystallized salt is separated from the liquor, and, if desired,washed with water, the washing liquor being added to the fresh mixtureof phosphoric acid and potassium chloride to be introduced into theliquor or' 1 better still being used for diluting the sulfuric acidacting on the raw phosphate to produce phosphoric acid.

The heating may be done directly or indirectly. 7 If operatinginsuitable apparatuses-such as revolving furnaces, tank fura I naces, etc,the process can'becarried through in a continuous manner, a mixture ofmother liquor, potassium chloride and phosphoric acid being continuouslyintroduced at one end of the furnace, while the solution to be cooledescapes at the other end.

Variousfchanges may be made in the details disclosed in the foregoingspecification without'departing from the invention or sacrificing theadvantages thereof.

In the claim affixed to this specification no selection of anyparticular modification of the invention is intended to the exclusion ofother modifications thereof.

I claim: v The process of producing mono-potassium means V 2 v V1,865,968

7 sium chloride comprising introducing potassium chloride and phosphoricacid in molecular proportion into a solution saturated both withmono-potassium phosphate KH PO and with the double salt KH PO .H POheating'the reaction mixture until the chlorine has been expelled, Whilemaintaining the percentage of Water in the mixture, cooling theresulting liquor, separating the monopotassium phosphate precipitated oncooling and utilizing the mother liquor in a succeedin operation. g

n testimony whereof I afl'ix my signature.

WALTHER soHUPP as v

